AutocarMcLaren P1 versus Porsche 918 Spyder - which is best?

As one of the few people who has driven both hypercars, Steve Sutcliffe delivers his verdict on which one he would take homeThis is by no conceivable stretch of the imagination a warts and all form of conclusion.
In fact, it isn't even a conclusion at all. But seeing as how I've driven both the Porsche 918 Spyder and McLaren P1 now, well, it would seem churlish not to offer at least some form of opinion about how two of the world's three maddest hypercars compare with one another.
So here are the facts, plus a bit subjective stuff thrown in for good measure.
One, the P1 is faster than the 918. Everywhere. On paper it looks close enough for there not to be much difference in the real world. But in that real world the McLaren feels of-another-solar-system quicker the Porsche. It feels as fast as anything I've ever driven to be honest, including Honda's 2007 F1 car, whereas the 918 feels merely very fast indeed.
Two, the P1 generates so much downforce in third gear and beyond when it's in Race mode that the 918 driver will not see which way it's gone around a circuit. They, McLaren, reckon the P1 generates as much as 5g of cornering force around corners like Blanchimont (at Spa) and Copse (at Silverstone), and having driven it around Bahrain, I believe them. The 918, on the other hand, doesn't even get close to that sort of grip.
Three, the driving position in the P1 is every bit as right and pure and perfect as the 918's - and the 918's is pretty much as good as it gets.
Four, the V8 engine in the P1 sounds not just sweeter but also more refined that of the 918, despite it being turbocharged (unlike the Porsche's).
Five, the P1 will, says McLaren, make money for the company - whereas, if pushed, Porsche bosses will admit that the 918 is a loss leader, a halo car that has cost the company money in the short term, even if they do manage to sell all nine hundred and eighteen 918 Spyders that are due to be built.
Six, the P1 spits bright blue flames out of its tail pipes if you give it full beans in a lowish gear. The 918 is far too sensible for that.
And finally, seven, the Porsche is just not as exciting to drive as the P1 generally, judging from my albeit fairly brief experience of both. You feel like you are right out there on the edge when driving the P1, especially in Race mode, with great big tail slides happening at the merest twitch of your right foot, even with the traction control system switched on. I never quite got that from the 918.
More time in both is, however, the only way to solve it once and for all...